Anyone know why I can get 30mb/s on my phone, but any device I tether to only gets around 6mb/s?
Are you using USB tether or Wifi, It is a fact that nothing replaces dedicated internet through an internet provider, also what program are you using, and if you are using the stock tether app, are you using it through entitlement change, another fact is what version is your OS? There are too many variables to factor in, we need more info to look into it.
Normally using tethering will drop anywhere from 5% to 15% on average. I am on the 247 leaked update, and my phone gets 27MB/s, and wifi tethering gets about 25MB/s. I am on unlimited data, and I pay for my tether app from Verizon.